$re = '/((\d+\.\d+)\s+)+(\d+)\s?(?=\w+)/m';
$str = '"""BEAVER COUNTY 001 0000
1010 BEAVER
2010 BEAVER COUNTY SCH DIST
0.008504
0.008508
4010 COUNTY SPECIAL SERVICE DIST NO.1 <---capture this 4010
4040 BEAVER COUNTY
8005 GREENVILLE SOLAR
0.004258
0.008348
...(more decimals)
0.008238
4060 SPECIAL SERVICE DISTRICT NO 7 <---capture this 4060
"""';
$subst = "\3";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php